Cheese compositions are generally prepared from dairy liquids by processes that include treating the liquid with a coagulating or clotting agent. The coagulating agent may be a curding enzyme, an acid, or a suitable bacterial culture or it may include such a culture. The coagulum or curd that results generally incorporates casein that has been suitably altered by the curding process, fats including natural butter fat, and flavorings arising during the processing (especially when using a bacterial culture as the coagulating agent). The curd is usually separated from the whey. The resulting liquid whey generally contains soluble proteins not affected by the coagulation; such proteins are, of course, not incorporated into the coagulum, because they are solubilized in the liquid whey.
The making of cheese is generally a labor-intensive process that requires large quantities of milk to develop any of the many popular varieties. Typically, cheese yields range from 6% to 12% depending upon the variety and moisture content of cheese. The remainder of the milk forms by-products. Whey is the single largest by-product from the milk during the cheese making process and, has often been viewed as a waste or low value by-product. Additionally, the whey contains potentially valuable components which are often lost. The whey protein is often dried or otherwise processed to remove it from the liquid whey. In the recent past, estimates for a commercial whey drier were typically in a range of about 5 to 10 million U.S. dollars. Commercial whey driers are also expensive from the standpoint of space and energy requirements. Commercial whey driers are typically large, and consume lots of energy.
Historically, cheese whey has been separated from curd and oftentimes discarded, sold or partly re-processed for recycling in a conventional cream cheese process. This typically is regarded as being not economical or feasible in some cases. In fact, unlike sweet whey from natural cheese manufacturing, the acid whey from cream cheese and cottage cheese has been deemed undesirable even for conversion or reprocessing into dry whey powder or whey protein concentrate due to its strong acid taste and for being impractical. In the conventional processes for making cream cheese, whey is formed and removed as mentioned in U.S. Pat. No. 6,416,797. Early efforts focused on better systems for separating whey from cheese curds are described in U.S. Pat. No. 2,387,276. Numerous other systems have been proposed over the years for separating the whey protein from liquid cheese whey. For example, various mechanisms for separating the whey from the liquid are disclosed in U.S. Pat. Nos. 3,642,492; 3,840,996; 3,873,751; 4,297,382; 4,497,836 and 4,617,861, to name only a few. Of course, several such systems may be used in conjunction with one another to separate and dry the whey protein.
Disposal of the whey is costly and difficult because the high protein and lactose content in cheese whey and high biological oxygen demand (BOD) can quickly contaminate wells and local streams and rivers. The high protein concentration can cause algae blooms in surface waters, and can render ground water unusable for many purposes.
Others have synthesized specially engineered proteins from cheese whey. There is, however, a limited demand for such proteins from acid whey due to its objectionable acidic off taste. When acidic whey or its by products (such as acid whey concentrate) are used in formulating food products, a neutralization step with an alkali (such as sodium hydroxide) is typically required. Consequently, excessive saltiness often results thus limiting its use.
Still other approaches rest on an appreciation that the high protein concentration of the whey might be desirable for use in health drinks and other nutritional snacks. However, the market for such specialty products is generally insufficient to keep whey protein prices adequate in comparison to their cost of production. This is due, in part, to the properties of the whey protein. Thus, it was estimated a few years ago that while cheese solids in mozzarella could be worth about $2.40–$3.60 (U.S.) per pound, the whey protein concentrate (34% protein) then could sell for about $0.58 (U.S.) per pound. Thus, due to the costs associated with drying and handling, the cheese producer usually sells its whey protein at a loss.
While some differences in costs might seem small, overall the costs are significant, especially since each year millions of pounds of acid whey are produced as a by-product. Added to that are the costs associated with the numerous steps required to turn milk into cheese having the desired characteristics of color, body, texture and organoleptic properties. Many of these steps are highly labor intensive and limit the speed and cost at which cheese can be produced. Additionally, success or failure in the market place is often determined by a company's ability to create cheese with the proper body, texture and organoleptic properties at the most competitive price. Because of the highly competitive nature of the cheese making industry, price differences of less than one cent per pound can provide significant advantages in the market place.
Thus, there has been a long-standing need for a method and related technology that can more effectively utilize acid whey obtained during the cheese making process to thereby increase profitability. Such a system should have reduced or no negative environmental impacts and should be relatively easy to use. It should be more energy effective. It should allow maximum recovery of cultured flavors, acids and dairy nutrients (e.g., minerals and vitamins) from the whey stream. It should yield cream cheese-like products and enable creation of other novel value-added dairy products with enhanced dairy flavors and nutrients having at least a potential to appeal and be accepted by customers and consumers. It should desirably yield products without wide variation in product characteristics. Because of the price sensitivity of the cheese market, the most profitable return for whey protein would be to return it into a cheese thereby increasing yield. The present invention provides such methods and products.